Hi Scott,
I love my D600. I upgraded a few months back from a D90. The difference was immediately appreciable—crisper images, better dynamic range, massive blow-up-ability, and great ergonomics. You may have read a bit about the sensor dust issue, and mine did accumulate some within the first 500 activations. I purchased a sensor cleaning kit and took care of it, and now it seems to be less of an issue.
Cheers, John

That is very helpful, I am running a D60 myself and had to clean the sensor which although nervous about worked out perfectly – I imagine the full frame will make an immense difference – it is probably as close to a Pro Camera that I can afford and the spec looks immense – Thanks for the feedback